hooking WndProc in hexchat

setwindowslongptr.py

from ctypes import *
from ctypes.wintypes import *
import hexchat
import traceback
import sys

__module_name__        = "sethook"
__module_version__     = "1.0"
__module_description__ = "Demonstration of calling SetWindowsLongPtr from ctypes"

WINDOWPROC = WINFUNCTYPE(LPARAM, HWND, UINT, WPARAM, LPARAM)

windll.user32.GetWindowLongPtrA.restype = c_void_p
windll.user32.SetWindowLongPtrA.argtypes = [HWND, c_int, c_void_p]
windll.user32.SetWindowLongPtrA.restype = c_void_p
windll.user32.CallWindowProcA.restype = c_void_p
windll.user32.CallWindowProcA.argtypes = [c_void_p, HWND, c_int, WPARAM, LPARAM]

def log(msg):
    ctx = hexchat.find_context(channel=">>python<<")
    if ctx:
        ctx.emit_print("Notice", "sethook", msg)

unload_hook = None

ENUMWINDOWSPROC = WINFUNCTYPE(BOOL, HWND, LPARAM)

def getLastError():
    errno = windll.kernel32.GetLastError()
    buf = create_string_buffer(128)
    windll.kernel32.FormatMessageA(0x1000, None, errno, 0, pointer(buf), 128, 0)
    return buf.value

def unload(arg):
    hexchat.unhook(unload_hook)
    result = windll.user32.SetWindowLongPtrA(foundHwnd[0], -4, OriginalWndProc)
    log("unload result: %x %d" % (result, result))
    log("Unloaded sethook")

currentThread = windll.kernel32.GetCurrentThreadId()
def enumWindow(hwnd, lParam):
    r = windll.user32.GetWindowThreadProcessId(hwnd, None)
    if r == currentThread and windll.user32.IsWindowVisible(hwnd):
        hwndOut = cast(lParam, POINTER(HWND))
        hwndOut[0] = hwnd
        title = create_string_buffer(128)
        windll.user32.GetWindowTextA(hwnd, title, 128)
        log("%s" % title.value)

    return True

unload_hook = hexchat.hook_unload(unload)

foundHwnd = pointer(HWND(0))
r = windll.user32.EnumWindows(ENUMWINDOWSPROC(enumWindow), foundHwnd)
if not r:
    log("Failed: %s" % getLastError())
OriginalWndProc = windll.user32.GetWindowLongPtrA(foundHwnd[0], -4)
if OriginalWndProc == 0:
    log("Failed: %s" % getLastError())
wrappedWndProc = WINDOWPROC(OriginalWndProc)

def init(ignored):

    def WindowProc(hwnd, msg, wParam, lParam):
        log("YO")
        return windll.user32.CallWindowProcA(OriginalWndProc, hwnd, msg, wParam, lParam)

    result = windll.user32.SetWindowLongPtrA(foundHwnd[0], -4, cast(WINDOWPROC(WindowProc), c_void_p))
    if result == 0 or result != OriginalWndProc:
        log("Failed: %d: %s" % (result, getLastError()))
    log("Loaded sethook")

hexchat.hook_timer(5000, init)